How come my 64 bit computer running Windows 7 is the only one that cannot get on the Internet?

Q: I have 4 computers running with a 4 port router. The one that has 64 bit windows 7 doesn’t want to log onto the internet automatically. A window comes up that says it can’t find a proper IP address while another compter is in use. I have to go through the “troubleshoot” procedure to get it on the internet or else shut the other computer down. The other 32 bit machines have no trouble at all. How can I fix this problem?